Control apparatus



March 17, 1959 J. F. WERR ETAL $877,835

CONTROL APPARATUS Filed April 12, 1957 2 Sheets-Sheet 1 J'RANSFORMERRELAY OVERLAP -87 INVENTORS JOHN E WERR RODGER C. WOLFGRAM EC-AM-ATTORNEY March 17, 1959 Filed April 12, 1957 J. F. WERR ET AL 2,877,835CONTROL APPARATUS 2 Sheets-Sheet 2 INVENTORS JOHN F. WERR RODGER C.WOLFGRAM BY ATTORNEY United States Patent 2,877,835 CONTROL APPARATUSJohn F. Werr, St. Louis Park, and Rodger C. Wolfgram,

Bloomington, Minn., assignors to Minneapolis-Honeywell RegulatorCompany, Minneapolis, Minn., a corporation of Delaware Application April12, 1951, Serial No. 652,568

Claims. Cl. 158-28) The present invention is concerned control apparatusand more burner controlapparatus. Present day requirements necessitatethat an acceptwith an improved able, burner control device providesafety switch action established 'at the end of this trial period, thesafety.

switch opens. to de-energize the burner. It is also desirable ;toprovide intermittent ignition, with. an ignition means timed by a timerto provide a trial ignition period.

It. isjan object of the present invention to. provide an. improvedburner control apparatus having a combined.

safety switch mechanism and ignition timing mechanism so inter-relatedboth electrically and mechanically with a flame detection mechanism thatsafe operation of the burner. is accomplished.

It is a further. object of the present invention to providean; improvedburner control apparatus having a bimetal timer which is latched in afirst position by means ofza movable. latch, the bimetal timer moving toa hot position torelease the latch, and having further means controlledby thecombustion responsive means which resets the latch to therebyreset the timer, this resetting action taking'place only in the eventthat the combustion responsive means first senses the presence ofcombustion and later senses the absence of combustion.

.More specifically, it is an object of the present invention' to'providean improved burner control apparatus having a single bimetal timer whichfunctions in one phase of its operation as a safety switch and in asecond phase of its operation as an ignition timer, the electricalcircuitry being such that in the event combustion is established, theoperation of the timer turns off ignition and the timer is reset by thecombustion responsive means upon the subsequent absence of combustion atthe fuel burner, and in the event combustion is not establishediheoperation of the timer actuates its switches to place theburnercontrol in the safety lockout condition.

These and other objects of the present invention will beiapparent tothose skilled in the art upon reference to the following specification,claims, and drawings, of which Figure l is a schematic representation ofthe electrical portionof the improved burner control apparatus alongwith, adiagramatic showing of the mechanical cooperation betweenthecombustion responsive means and .the timer..

Figure 2 is a view, partially in section, of the latch member,thebimetal' member and the movable member positioned bythe'combustionresponsive means,showing the position of these elements 'as shown inFigure 1,

1 ili'tlie run position, and

specifically with an improved Figure 4 is a showing of a portion of theapparatus of Figure l in the safety lockout position.

Referring specifically to Figure 1, the improved burner controlapparatus is shown within the broken line 10. This burner controlapparatus is connected to control the operation of a burner unitdesignated generally by the reference numeral 11 having a burner motor12 which controls the flow of fuel to a fuel nozzle 13. The fuel at thenozzle 13 is ignited by a pair of ignition electrodes 14 connected to anignition transformer 15. Electrical power is supplied to the burner unit11 by means including terminals 16, 17, 18 and 19 of a burner controlapparatus 10.

The need for operation of the burner unit 11 is sensed by means of athermostat 20 which is connected to terminals 21 and 22 of the controlapparatus 10 and functions to close its switch upon such a need. I

Electrical power for both the burner control apparatus 10 and the burnerunit 11 is received from power line conductors 23 and 24 whichconductors are connected to a source of alternating voltage, not shown.

The power supply conductors 23 and 24 are connected This timing means isin the form of a bimetal timer having an ambient temperaturecompensating bimetal 33' igu're B is-ashowing of a portion of theapparatus in to the primary winding 25 of a transformer relay 26 havinga secondary winding 27 and a movable armature 28 which controls theoperation of switches 29 and 30. The secondary Winding 27 of thetransformer relay functions to both supply electrical energy tocomponents within the burner control unit 10 and to control the positionof armature 28. In other words, upon an electrical circuit beingcompleted through the secondary- Winding 27, the armature 28 is movedfrom the position shown in Figure l to a position wherein the switches29 and 30 of the relay are closed. This cooperation has been showndiagrammatically by means of the broken line connection designated bythe reference numeral 31.

The reference numeral 32 designates a timing means.

and an active bimetal 34. A timer actuator, in the form of a heater 35,is closely associated with the active bimetal 34 and causes the lowerend of this bimetal to move to the right when the heater is energized.The movement of the lower end of the active bimetal 34 has beenindicated in Figure 1 by provision of an arrow and the letter H.

'The lower end of compensating bimetal 33 is rela- .-tively fixed inposition while its upper end is mounted on one side of the pivot of apivoted yoke 36. The upper end of the active bimetal 34 is mounted onthis yoke 36 on the other side of the pivot from member 33.

I The reference numeral 37 designates generally a movable operatingmember, or a latch member. Member 37 is pivoted at pivot 38 and isbiased for counter-clockwise rotation about this pivot by means of aspring 39 having one end fixed in position at 40 and having the otherend connected to member 37 at 41.

Member 37 is also provided With a knee portion 42 which engages thelower end of the active bimetal 34 when the bimetal 34 is in its coldposition, as shown in Figure 1. The member 37 has an extension portion43 are separated by an insulating spacer 46. In the position shown, thatis the first position of member 37, the switch blade 44 engages contact47, and switch blade 45 engages contact 48 and is disengaged fromcontact 49. As will be described, upon energization of heater 35, whichin turn causes active bimetal 34 to move to the right, member- 37rotates counter-clockwise about its pivot 38 and causes switch blades 44and 45 to move in an upward rotation of wheel 54.

direction, switch blades 44 and 45 thereby disengaging contacts 47 and43 respectively, and switch blade 45 engaging contact 49.

. As will be apparent, the operation of the switches including switchblade 45 and contacts 48 and 49 must have an overlapping action. Thatis, switch blade 45 is so constructed and arranged with respect tocontacts 48 and 49 that it engages one of the contacts beforedisengaging the other as the switch blade 45 moves in an upward or adownward direction.

The combustion responsive means of the burner control apparatus isdesignated generally by the reference numeral 50. This combustionresponsive means includes a spiral shaped bimetal operator 51 which hasone end thereof fixed in position at 52 and has the other end thereofconnected by means of the shaft designated by the broken line 53 to thecenter of a wheel 54. The operation of the combustion responsive meansthus far described is such that the spiral shaped bimetal 51 causesrotation of the wheel 54 in a clockwise direction upon a temperaturerise, as shown by the arrow in Figure l, and likewise causes rotation ofthe wheel 54 in a counterclockwise direction upon a temperature fall.The wheel 54 is provided with a recessed portion, or valley, around thecircumference thereof. The bottom of this recessed portion is shown inFigure 1 by means of the broken line designated by the reference numeral55.

This recessed portion of the wheel 54 is engaged in a slip frictionmanner by a finger-like extension 56 of a spring biased member or rod57. This rod 57 is carried in a harness 58 which is pivoted at 59. Theharness 58 is provided with an upper extension 60, which extension isprovided with a hole designated by the reference numeral 61. This holereceives the rod 57 and once the rod 57 is placed in position, a pin, orlook washer of some sort is placed in position as indicated by thereference numeral 62. The washer 62 provides an upper abutment for acoil spring 63 and the surface of the member 58 designated by thereference numeral 64 provides the lower abutment. In this manner, therod 57 may move through the holes provided in the harness 58 under thebias of the spring 63 and limited by 62-61.

Member 88 couples the rod 57 to a combustion responsive switch meansincluding switch blades 73, 74, and 75. In the absence of combustion,switch 73-74 is closed while switch 73-75 is opened. Upon combustionbeing established, switch 73-90 opens and switch 73-75 closes.

Explaining the operation of the wheel 54 and the manner in which itcooperates with the spring biased rod 57, upon the combustion responsivebimetal 51 being subjected to a temperature rise, wheel 54 moves in aclockwise direction. Due to the friction between the portions 56 ofspring biased rod 57 and the groove provided in the circumference ofwheel 54, the harness 58 pivots about pivot 59, moving from right toleft in Figure 1. This movement continues until the rod 57 has movedsubstantially up to the left of the center of rotation of the wheel 54,see Figure 3. Upon a subsequent temperature fall as experienced bybimetal 51, wheel 54 moves in a counter-clockwise direction and therebycauses the spring biased rod 57 and its harness 58 to move about pivot59 in a clockwise direction that is to return to the position shown inFigure 1. This movement continues until the extension 56 of springbiased rod 57 is substantially to the right of the center of the In thisposition, member 88 has followed'movement of rod 57 and thereby opensswitch 73-75 and closes switch 73-74.

The support harness 58 of spring biased rod 57 is provided with anextending arm 65. This extending arm has a spring blade 66 fixed to theend thereof. As can be seen more clearly in Figure 2, this spring 66extends through an opening 67 provided in the latching member 37.

In FigureZ, portions of .the spring blade 66, themem ber 65, the bimetal34, and the latch 37 have been shown in section. From this view'it canbe seen that with the elements of the burner control apparatus 10 in theposition shown in Figure 1, the spring blade 66 does not engage thelatch member 37.

However, upon operation of the timer 32 to cause the bimetal 34 to moveto the right and thereby release the latch 37, and upon the combustionresponsive bimetal 51 experiencing a temperature rise which isfollowed'by a temperature fall, the spring blade 66 is operative 'toengage the upper right hand surface of the opening "67, this surfacedesignated by the reference numeral 68, and as movement of the springbiased rod 57 and its harness 58 continues in a clockwise direction thelatch 37 is caused to rotate in a clockwise direction against the biasof spring 39 to move to a position wherein the bimetal 34 may once againassume its'cold position, that is the position shown in Figures land 2.

Considering this phase of the operation of the device in greater detail,and with reference to Figure 2, upon wheel 54 rotating in acounterclockwise direction, spring 66first engages latch member 37 atthe surface 68. As wheel 54 continues to rotate, spring 66 is bowed, thelower end bowing concave upward to the right. This bowing occurs due tothe increasing force which is building up in spring 39 as latch member37 rotates about its pivot 38. When latch member 37 has rotated asufiicient amount to allow bimetal 34 to again assume'its cold position,the force exerted by spring 39 is sulficiently great to cause spring 66to bow to the extent that spring 66 snaps through the opening 67p'rovidcd in latch member 37.

The elements making up the combustion responsive means 50 and the timingmeans 32 are so proportioned and arranged so that upon wheel 54 firstrotating in a clockwise direction and then returning by rotation in acounter-clockwise direction, the spring 66 first engages latch member 37to reset switch 45-48 to the position shown in Fig. 1. The spring 66then snaps through the opening 67 provided in latch member 37 and latchmember 37 remains in position due to bimetal 34, as shown "in Figures 1and '2. The last event in pointof time is the resetting of switch 73-74to the position shown in Figure 1. Such a construction insures that theburner unit 11 may not be re-energized until spring 66 has moved to theposition shown in Figure 2 wherein the latch member 37 is under the solecontrol of bimetal '34, to thereby insure that the device is capable ofassuming the safety lockout position as shown in Figure 2.

l is shown in its standby condition, that is electrical power issupplied to the power line conductors 23 and 24, the

. circuit for the secondary winding 27 of transformer relay 26 is open,the switch of thermostat 20 is openindicating there is no need for theoperation of'the burner unit 11,

the bimetal timer 32 is in its cold position with heater 35de-energized, and the combustion responsive means 50 is sensing theabsence of flame at the burner unit 11.

Assume now that the thermostat 20 closes its switch to indicate the needfor operation of the burner unit 11. This completes an energizingcircuit for the secondary winding 27 of transformer relay 26. Thisenergizing circuit can be traced from the right hand terminal ofsecondary winding 27 through thermostat 20, conductor 69, switch blade45, and contact 48, conductor 70, heater 35, conductors Hand 72, switchblade 73 and contact 74, and conductors 76 and 77 to the left handterminal of secondary winding 27. From the above traced circuit it canbe seen that the secondary winding 27 of the transformer relay cannot beinitially energized unless the start contacts 45-48 are closed, unlessthere is electrical was continuity in the heater 35, and unlessthecombustion responsive mea'nsswitch'73-74 is'in' the position indicat--ing the absence of flame at the burner unit 11.

Energization of the secondary winding 27 causes the armature 28 oftransformer relay 26 to move in a downward direction thereby closingswitches 29 and 30. The closing of switch 30 completes an intermediateenergizing circuit which shunts the switch 73-74 controlled bycombustion responsive means 50. This shunt circuit can be seen bytracing a circuit from contact 74 through conductors 76 and 78, switch30, and conductors 79 and 72 to switch blade 73. Therefore, theintermediate energizing circuit for secondary winding 27 is notdependent upon the combustion responsive switch means 73-74 being in itsclosed condition. v

The closing of switch 29 by transformer relay 26 completes an energizingcircuit for both the burner motor 12 and the ignition transformer of theburner unit 11. The energizing circuit for motor 12 can be traced frompower line conductor 23 through conductors 80 and 81 to the burner motor12 and then by means of conductors 82, 83 and 84, switch 29 andconductor 85 to the other power line conductor 24. The energizingcircuit for the. ignition transformer 15 includes in part conductor 86,switch blade 44 and contact 47, and conductor 87. From these circuits itcan be seen that energization of the burner motor 12 depends solely uponthe switch 29 of the transformer relay being closed. However,energization of the ignition transformer 15 not only depends upon switch29 being closed but also upon the switch 44-47 being closed.

- A flame is now normally established at the burner unit 11. The heatfrom this flame causes the combustion" responsive bimetal 51 toexperience a temperature rise. This in turn causes wheel 54 to move in aclockwise direction. As has been above described, this causes the springbiased member 57 and its harness 58 to rotate in a counter-clockwisedirection about the pivot 59, thereby causing switch 73-74 to open andswitch 73-75 to close through movement of the member 88.

As has been described, since the relay operated switch 30 is now in theclosed condition, the energizing circuit for the secondary winding 27 nolonger depends upon switch 73-74 being in the closed condition. Theclosing of the switch 73-75 completes a portion of a holding circuit forthe secondary winding 27. The operation of this holding circuit will nowbe more completely described. I It will be remembered that the initialenergization of thesecondary winding 27 of the transformer relayincluded the actuating heater 35 of the bimetal timer 32. Therefore, theactive bimetal 34 immediately starts to warp and causes its lower end tomove to the right. Referring now to Figure 3, a portion of the burnercontrol apparatus of Figure 1 is shown with the combustion responsivemeans 50 in the of flame at the burner unit its actuated position.

10 and with the timer 32 in In this position the wheel 54 has rotated ina clockwise direction and has caused rotation of the spring biased rod57 and its harness 58 in a counter-clockwise direction about the pivot59. This causes the switch 73-74 to assume its open condition, and theswitch 73-75 to assume its closed condition. This has also caused thespring blade 66 to move up and out of the opening 67 provided in thelatch member 37. The active bimetal 34 of the bimetal timer 32 has beenheated to an extent by the heater 35 such that it has re eased the latchmember 37 and this latch member has rotated in a counter-clockwisedirection about pivot 38 to thereby cause switch 44-47 to assume an opencircuit condition and has caused switch. 45-49 to assume a closedcircuit condition. Referring again to Figure 1, it will be rememberedthat the operation of switches 45-48 and 45-49 is an overlapping action.words, the switch 45-49 is first closedbefore switch position sensingthe presence,

In other 45-48 opens. This completes the above mentionedhoiding'c'ircuit for the secondary winding 27 of the transformer relay.This holding circuit can be traced from the right hand terminal ofsecondary winding 27 through thermostat 20, conductor 69, switch blade45 and contact 49, conductor 89, contact 75 and switch blade 73,conductors 72 and 79, switch 30, and conductors 78 and 77 to the lefthand terminal of secondary 27.

A very short period of time thereafter, the switch 45-48 opens. This isthe starting interlock switch of the timer 32 and this switch opens theinitial energizing circuit of the secondary winding 27, previouslytraced. Since the running circuit, above described, is now complete thesecondary winding 27 remains energized and electrical power is suppliedto the burner unit 11. How'- ever, this electrical power is suppliedonly to the motor 12 since the ignition transformer 15 is nowde-energized. As the bimetal 34 of timer 32 moved to the right, thelatch member 37 was released and moved in an upward direction, such asshown in Figure 3. This caused spring blade 44 to disengage contact 47and thereby open the energizing circuit for ignition transformer 15.

Assume now that there is no longer a need for operation of the burnerunit 11; this is evidenced by thermostat 20 opening its switch. This inturn deenergizes the secondary winding 27 of transformer relay 26 andthereupon causes the switches 29 and 30 to assume their open condition,such as shown in Figure 1'. The opening of switch 29 de-energizes burnermotor 12 and causes the flame at the burner unit 11 to be extinguished.Considering the burner control apparatus at this instant, the relayoperated switches 29 and 30 are open, the flame responsive switch 73-74is open and the switch 73-75 is closed, the timer operated switches44-47 and 45-48 are open, and the timer operated switch 45-49 is closed.Therefore, should there be an immediate recall for operation of theburner unit 11, such as evidenced by closing of the switch ofthermostat20, the secondary winding 27 of the transformer relay cannotbe energized since both the initial energizing circuit and the runningcircuit are open. The initial energizing circuit is open at both thestart switch 45-48 of timer 32 and at the switch 73-74 controlled bycombustion responsive means 50. The running circuit is open at the relayoperated switch 30. Therefore not only must the bimetal 51 of thecombustion responsive means 50 return to its cold position to close theswitch 73-74 but also, the latch member 37 must be returned to itslatched position as shown in Figure 1, this being accomplished bymovement of spring blade 66 as the combustion responsive means wheel 54rotates ina' counter-clockwise direction and thereby causes clockwiserotation of spring bias rod 57 and its harness 58.

Upon rod 57 returning to its cold position, the spring 66 first engageslatch member 37 to close starting switch 45-48. The spring 66 thenpasses through the opening 67 in latch member 37 so that the latchmember is now maintained in position by bimetal 34. Then combustionswitch 73-74 closes. The secondary winding 27 of transformer relay 26may now be energized in the event that the switch of thermostat 20 isclosed at this time.

Assume now that there has been such an additional need for operation ofthe burner unit 11. As above de-' scribed, this causes transformer relay26 to be energized, motor 12 and ignition transformer 15 to beenergized, and heater 35 of timer 32 to be energized. Further assume,that, due to malfunction of the burner unit 11, flame has notestablished at the burner unit. In 'this' event, the combustionresponsive means 50 remains in the condition shown in Figure l and theburner control apparatus 10 assumes-the safety lockout position as shownin Figure 4.

Referring to Figure 4, this figure shows the bimetal timer 32 in itsactuated condition. In other words, the heater 35 has been energizedfora suflicient time peiio'd to cause the bimetal 34 to move to theright and release latch member 37. Latch member37 thereby rotates in acounter-clockwise direction about the pivot 38 and under the bias ofspring 39. This movement of member 37 causes the starting switch 4548 tobe opened and causes the switch 45-49 to be closed. However, since thecombustion responsive means 50 has not detected the presence of flame,the combustion responsive switch 73-'-75 remains in its open positionand arunning circuit cannot be established for the secondary winding 27of the transformer relay. Therefore, the secondary winding 27 isde-energized. This in turn de-energizes the heater 35 of bimetal timer32. After a time period, the bimetal 34 cools-but cannot return to itscold position .due to latching member 37, shown in Figure 4, engagingthe lower end of bimetal 34 to prevent movement to the left.

The apparatus isnow in its safety lockout position in which thethermostat 20 no longer controls operation of the burner unit 11. Inorder to reset the burner control apparatus, a raised portion or resetknob Q is provided to cause rotation of the wheel 54. It willberemembered that the combustion responsive bimetal 51 has notexperienced a temperature rise due to the lack of the establishment offlame at the burner unit 11. However, by rotation of the knob 90 in theclockwise direction, thereby simulating the temperature rise at thebimetal 51, the spring biased rod 57 and its harness 58 are moved in acounter-clockwise direction about pivot 59. This causes the springmember 66 to move to the position shown in Figure 3. The operator nowreleases theknob 90 and the wheel 54 rotates in a counter-clockwisedirection under bias of the bimetal 51 which has been stressed bymanually twisting it in the clockwise direction as above described. Thiscauses the spring blade 66 to move in a downward direction and to engagethe surface 68 of the latch member 37, which-surface can be seen inFigure 2. This causes the latch member 37 to move in a downwarddirection, rotating clockwise about pivot 38 and thereby resets thetimer 32 to its cold position as shown in Figure 1. Therefore, theburner control apparatus has been manually reset from the safety lockoutposition in Figure 4 to the standby position of Figure l and upon asubsequent call for operation of the burner unit 11 the burnerunit ll-isagain controlled in the normal manner as above described.

From the above description it can be seen that We have provided animproved burner control apparatus providing ignition timing and safetyswitch timing with a minimum number of components and therefore theresultant minimum cost. 7

We claim as'our invention:

1. Burner control apparatus for use with a fuel'burner comprising: atemperature responsive element adapted to be positioned to be heated byflame at the fuel burner, a switch arranged to be controlled bysaid'temperature responsive element to be actuated from an open to aclosed condition upon flame being detected at the fuel burner, amovablemember controlled by said temperature responsive element andmovable froma first to a-second position upon said temperature responsive elementsensing the presence of flame at the fuel burner, said movable membermoving from said second to said first position upon said flame detectorsubsequently sensing the absence of flame at the fuel burner, a timerhaving an electrically energizable actuator and a timer member movablethereby after a time period of energization of said timer actuator, astarting switch, said starting switch being normally in the closedcondition, a latch member jointly controlled by said timer member and'saidmovable member and arranged initially to maintain said startingswitch in the closed condition and to latch said starting switch in openposition after a predetermined time period of energization of said timeractuator, said movable member being arranged to control said'latchmember and thereby cause said starting switch to again assume its closedcondition upon said movable member moving from said second tosaid firstposition in response'to said tempera ture responsive element firstsensing the flame at the fuel burner and then subsequently sensing theabsence of flame at the fuel burner, a relay having an electricallyenergizable actuator and a switch controlled thereby, energizing circuitmeans for'said relay actuator including terminals adapted to beconnected to means responsive to the need tor operation of the fuelburner and including said timer actuator and said starting switch,circuit means including terminals adapted'to be connected to the fuelburner controlled by said relay switch and adapted to energize said fuelburner upon said relay actuator being energized, and running circuitmeans for said relay actuator including said switch controlled by saidtemperature responsive element, said running circuit being completedupon said temperature responsive element detecting flame at. the fuelburner.

2. Burner control apparatus for use with a fuel burner having meansresponsive to the need for operation of the fuel burner, comprising: aflame detector arranged to be located to sense the presence or absenceof flame at the fuel burner, a normally open switch controlled by saidflame detector and movable to a closed position upon a flame beingdetected at the fuel burner, a movable member controlled by said flamedetector and movable from a first to a second position upon said flamedetector detecting flame at'the fuel burner, said movable member movingfrom said second to said first position upon said flame detectorsubsequently detecting the absence (of flame at the fuel burner; a timerhaving an electrically energizable actuator and timer means movablethereby after a time period of energization of said timer actuator, afirst normally closed switch, a second normally open switch, a latchmember controlled jointly by said timer means and'saidflame-detector-co-ntrolled movable member and arranged to latch saidfirst and second switches in the open and closed conditions respectivelyaftera time period of energization of said timer actuator, said flamedetector movable member being arranged to move said latch member as saidmovable member moves from said second to said first position to therebycause said first and second switches to assume the'close'd and openpositions respectively upon said flame detector detecting the absence offlame at the fuel burner subsequent tothe detection of the presence offlame at the fuel burner; relay means having an electrically energizableactuator and a normally open switch controlled thereby, initialenergizing circuit'means for'said relay actuator including terminalsadapted to be connected to the means responsive to the need foroperation of the fuel burner and including said first switch and saidtimer actuator, and a running energizing circuit for said relay actuatorincluding said second switch and said flame detector switch.

3. Burner control apparatus for use with a fuel burner having ignitionmeans and means responsive to the need for operation of the fuel burner,comprising: flame detecting means responsive to flame at the fuel burnerunit, a first and a second switch controlled by said flame d'etectingmeans, said first switch being closed in the presence of flame and beingopen in the absence of flame and said second being closed in theabsence'of flame and open in the presence of flame, a movable membercontrolled by said flame detecting means and movable from a first to asecond position in response to the establishment of flame at the fuelburner, said movable member being moved from said second to'said firstposition in response to the subsequent absence'of flame at the fuelburner; timer means having a movable member and an electricallyenergizable actuator therefor,'said timer movable'mernber being movablefrom a first to 'a second position after a predetermined time period ofencrgization of said actuat'o'r; latch means 'arrangedunder the controlof said flame detecting means movable member and said timerm'ovabl'e'm'ernber, said latch means moving from afirst to a secondposition upon said timer movable member moving from said first to saidsecond position after a timer period of energization of said timeractuator, said flame detecting means movable member controlling saidlatch means to reset said latch means to its first position upon saidflame detecting means movable member moving from its second to its firstposition; a first normally closed switch, a second normally open switch,and a third normally closed switch controlled by said latch means andmoved from the normal condition when said latch means moves to saidsecond position; a relay having an actuating winding and a switchcontrolled thereby, said relay switch moving to a circuit closingposition upon energization of said relay winding, initial energizingcircut means for said relay winding including terminals adapted to beconnected to the means responsive to the need for operation of the fuelburner and including said first normally closed switch, said timeractuator and said second flame detecting means switch, a holdingenergizing circuit for said relay winding including said second normallyclosed switch and said first flame detecting means switch, andenergizing circuit means for the fuel burner including said relay switchand including an energizing circuit for the burner ignition means underthe control of said third normally closed switch.

4. Burner control apparatus for use with a fuel burner having ignitionmeans and means responsive to the need for operation of the fuel burner,comprising: flame sensing means in the form of a spiral bimetal elementarranged to be positioned to be heated by flame at the fuel burner unit,a wheel fixed to said bimetal and arranged to be rotated in a firstdirection upon a flame being established at the fuel burner unit and tobe rotated in an opposite direction upon the subsequent absence of flameat the fuel burner unit; a spring biased member positioned to engage theouter circumference of said Wheel in a slip friction engagement, saidspring biased member being pivoted such that said spring biased membermoves from a first side of said wheel to a second side of said wheelupon fiame being established at the fuel burner, said spring biasedmember subsequently returning to said first side upon the subsequentabsence of flame at the fuel burner; a first and second switchcontrolled by said spring biased member, said first and second switchesbeing opened and closed respectively when said spring biased member ison the first side of said wheel and being closed and opened respectivelywhen said spring biased member is on the second side of said wheel; atimer having a bimetal operating member and an operating heatertherefor, latching means including a movable member arranged to be heldin a first position by said bimetal when said bimetal is in its coldcondition, said bimetal moving to its hot position after a predeterminedtime period of energization of said heater and allowing said movablemember to move to a second position; switch means including a first,second and third switch controlled by said movable member, said firstand third switches being closed when said movable member is in saidfirst position and said second switch being closed when said movablemember is in said second position; further means controlled by saidspring biased member arranged to reset said movable member to said firstposition upon said spring biased member moving from said second to saidfirst side of said wheel upon a flame being established at the fuelburner and subsequently becoming extinguished; a relay having anenergizing winding, energizing circuit means for said relay windingincluding terminals adapted to be connected to the means responsive tothe need for operation of the fuel burner unit and including the firstswitch controlled by said movable member, said bimetal heater, and thesecond switch controlled by said spring biased means; a first and secondswitch controlled by said relay, energizing circuit means for the fuelburner including the first of said relay switches to energize the fuelburner and to energize the fuel burner ignition means through said thirdswitch controlled by said movable member; and a running circuit for saidrelay Winding including the second switch controlled by said movablemember, the first switch controlled by said spring biased means, andsaid second relay switch.

5. In combination, a spiral shaped bimetal element having one endrigidly fixed in position, a wheel having its center fixed to the otherend of said bimetal element so that upon heating or cooling of saidbimetal said Wheel rotates about its center, a spring biased memberbeing pivoted at one end thereof and positioned such that the other endthereof bears against the outer circumference of said wheel, said springbiased member thereby being caused to move about its pivot as said otherend thereof follows movement of said wheel in accordance With thecondition to which said bimetal is subjected, a timer having a bimetaland a heater fixed in close proximity thereto, a latch member arrangedto engage an end of said bimetal, said bimetal restricting the movementof said latch member in the cold position and in the hot positionreleasing said latch member for movement thereof, a further memberpositioned by said spring biased member and cooperating with said latchmember to reset said latch member to its latched position, therelatching being accomplished upon said spiral shaped bimetal elementbeing subjected to a temperature rise and a subsequent temperature fall,and means controlled by said latch member.

References Cited in the file of this patent UNITED STATES PATENTS

